(Topic ID: 245488)

Sys 7 circuit board in dishwasher


By Andy_B

9 months ago



Topic Stats

  • 14 posts
  • 8 Pinsiders participating
  • Latest reply 9 months ago by barakandl
  • Topic is favorited by 1 Pinsider

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    #1 9 months ago

    I've removed the diagnostic switch. Do I have to remove the LED or should it be OK?

    #2 9 months ago

    The LED should be OK. About the only other component I would worry about would be the flipper relay, and possibly the crystal.

    #3 9 months ago

    What are you trying to achieve by doing this?

    I definitely would not put those boards in a dishwasher. Those boards were never designed for that kind of stress. Plus they are now 30+ years old. Get a can of electronics cleaner and spray it down. If you don't want to do that, then buy a spray bottle and isopropyl alcohol. Or just pour iso alcohol over the board.

    #4 9 months ago
    Quoted from Turtle:

    What are you trying to achieve by doing this?

    Get it clean?

    I definitely would not put those boards in a dishwasher. Those boards were never designed for that kind of stress. Plus they are now 30+ years old. Get a can of electronics cleaner and spray it down. If you don't want to do that, then buy a spray bottle and isopropyl alcohol. Or just pour iso alcohol over the board.

    I've done it to several other boards with no problem. It's just water and detergent. The key is to remove the board before the drying cycle.

    #5 9 months ago
    Quoted from uncivil_engineer:

    The LED should be OK. About the only other component I would worry about would be the flipper relay, and possibly the crystal.

    Yeah, always wondered how well sealed the crystal is but never had an issue with it when I have done this previously. No flipper relay on Sys 7 board though.

    #6 9 months ago

    LED's and crystals are sealed.
    Switches and relays are not sealed.

    System 7 -- CPU board has DIP switches. These are not sealed and over time will often develop a nice blue-green corrosion on the contacts. As long as a switch stays open or closed - no problem. If you change from open to closed with the corrosion, they don't always register as 'closed'.

    #7 9 months ago
    Quoted from Turtle:

    What are you trying to achieve by doing this?
    I definitely would not put those boards in a dishwasher. Those boards were never designed for that kind of stress. Plus they are now 30+ years old. Get a can of electronics cleaner and spray it down. If you don't want to do that, then buy a spray bottle and isopropyl alcohol. Or just pour iso alcohol over the board.

    I have also done this with a few board sets. It is a pretty easy way to clean them up. It even gets under the chips. After I run them through the dishwasher, I usually let them dry for at least a couple of days. Given that I live in a desert where the humidity averages around 30%, getting things to dry is never a problem.

    -2
    #8 9 months ago

    would you put your TV in a dishwasher?

    #9 9 months ago
    Quoted from wdennie:

    would you put your TV in a dishwasher?

    Certain individual components/boards? If they were dirty, absolutely. Having worked in an electronics lab for a short time at a nuke plant, the first thing we did with malfunctioning equipment with circuitry was to remove the board or component, throw it in the dunk tank, dry it in the oven for a couple hours, then plug it back in and see if it functioned correctly.

    #10 9 months ago

    I wash them under sink faucet with tooth brush and dish soap. Fling off and blow out the majority of the water. Then sit in front of a box fan for a couple hours. Unless the board is burned they usually come out looking sharp compared to before washing. The amount of smoke/dust/crud that accumulates on many boards over 30 years is amazing and pretty gross.

    Not all system 7 boards don't have dip switches but I think some early ones do. I will honestly wash boards with dip switches. I avoid drenching them but also make sure to blow out the water best as possible. A wet dip switch can for sure cause problems tho. In a Bally game wet dip switches will cause switch errors. Are the LED digits sealed? I don't know but probably are. The plastic box flipper relay on the driver board is not sealed and water will get trapped inside of it.

    #11 9 months ago

    Nearly every LED digit I've ever seen is sealed. Only ones I've seen that aren't are the ones with integrated BCD decoders.

    Truth is, you'd be surprised how many boards go though a water wash cycle as part of their manufacture. It all depends on the parts, fluxes, and other criteria which ones do and which ones don't. And a purpose built wash for circuit boards? Your home dishwasher won't even come close to that level of heat, water pressure, and air pressure. I'm sitting about 50 feet from one of them right now.

    If you use a water soluble flux, it's actually required to wash them with hot water, under high pressure, or the boards start to corrode over time.

    -Hans

    #12 9 months ago
    Quoted from G-P-E:

    LED's and crystals are sealed.
    Switches and relays are not sealed.
    System 7 -- CPU board has DIP switches. These are not sealed and over time will often develop a nice blue-green corrosion on the contacts. As long as a switch stays open or closed - no problem. If you change from open to closed with the corrosion, they don't always register as 'closed'.

    Thanks Ed.

    No DIP switches on this one though.

    20190619_194538 (resized).jpg

    It does appear to have been jumpered for 2732 chips at IC14, IC17 and IC20. Is this common?

    20190619_200043 (resized).jpg

    #13 9 months ago

    With that ROM set, I'd venture it was used in a Hyperball, but they didn't have any 2532's.

    #14 9 months ago
    Quoted from HHaase:

    Nearly every LED digit I've ever seen is sealed. Only ones I've seen that aren't are the ones with integrated BCD decoders.
    Truth is, you'd be surprised how many boards go though a water wash cycle as part of their manufacture. It all depends on the parts, fluxes, and other criteria which ones do and which ones don't. And a purpose built wash for circuit boards? Your home dishwasher won't even come close to that level of heat, water pressure, and air pressure. I'm sitting about 50 feet from one of them right now.
    If you use a water soluble flux, it's actually required to wash them with hot water, under high pressure, or the boards start to corrode over time.
    -Hans

    Water soluble flux is awesome. I use Kester 24-6337-6403 when assembling new PCBs. Rinse under warm water with a little toothbrush action and all the flux comes off easily. Dang rosin flux is a pain to clean. No clean flux looks like hell to leave on a PCB and just as hard to remove as rosin. I will even use water soluble flux when doing rework where I know im going to wash the board later. Under PF stuff, rosin.

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